Set a specifc renewal date for a product / Proratd Billing

Verzoek

We need the ability to be able to set prorated billing so that we can set a specific renewal date for a chosen product. So for example Server product "Dedi1" has a renewal date each month on 28th. Also ability to make cost prorated so if customer makes order after a set date like 15th they would need to pay for 15th to 28th + 1 Month. For example in other product check WHMCS.